Tim P. Whitby/Getty Images(LOS ANGELES) -- Many Sarah Jessica Parker fans were shocked when the actress went off on a Twitter user last month in a series of pointed tweets. And because the user deleted the offending tweet, fans were left to wonder what upset Parker so much...until now.

In an interview with The Edit, Parker revealed the Twitter user questioned if she was the biological mother of her twins, Marion and Tabitha.

"Other people can be mean, and that's something I just have to make peace with. That was my worry before engaging in social media; I was afraid of it," she explained. "I see mean stuff every day: when I look at Twitter I scroll with one eye open and one closed. That particular day, it was just one of the things I saw."

"She, not subtly at all, said that my children are not my children. There have been a few -- let's say half a dozen -- times in my career when I have wanted to respond. I don't want to encourage people picking on her, because that's no better. But I wrote back, ‘What? Like, is this fun?' She never responded and deleted it," she continued.

"I don’t talk about my marriage; I am circumspect about my children. I sometimes regret that people don’t understand all that I do and all that I am because I am embarrassed to talk about what I’ve accomplished -- I think it sounds self-centric and narcissistic. So I can't figure out what she hated so much about me that she did that. And I just can't imagine anything lower than that," Parker added.

Initially when Parker responded to the mean tweet, she wrote: "Your anonymity doesn't diminish your outrageous and vulgar tweet. And your deletion only reveals your cowardice. ...I'm certain there isn't a woman on this planet who would support your specific kind of cruelty. No apology, no explanation."

Along with their 4-year-old twins, Parker and Broderick have an 11-year-old son, James Wilkie. The two wed in 1997.